2007 500 4x4 manual keeps losing its timing...

[Mike Curtis]

Hi guys, I'm new here and new to Arctic Cat. This is my first post. And I need help. I just got a 2007 500 4x4 manual quad that did not run. The guy that I bought it from said he just rebuilt the top end. He thought that it jumped time. I have the manual and it doesnt seem to be detailed enough.

First thing I did was set valve lash. It checked good. No start...

Second pulled valve cover assembly. Removed timing tensioner and chain from cam. Positioned cam and reinstalled everything per. spec. and readjusted valve lash. tried to start and presto!! It fired right up!!! It ran for about 20 seconds and died. So I started it up again and it ran for five seconds and died... I could not get it to restart. So I put it back to tdc  " using stator mark" and pulled valve access covers... Zero valve lash.  So I pulled the valve cover again and the cam was 90 degrees off... I repeated this process 4 times in a row with the exact same results... does anyone have any knowledgeable experiences  with this kind of situation? I'm starting to think that it's a severely stretched timing chain, bad tensioner or guide, I'm also looking at the automatic decompression element of the camshaft... I am a little stumped, and any help would be greatly appreciated!!! Thanks in advance...

[davefrombc]

Check the sprockets They  should be keyed to the shafts and if there's a key  missing the sprocket will slip  on the shaft.  Unless the chain  is very  slack  it  should  not  jump   on the sprocket teeth.  Those  are the only  two  ways I  can see it  physically  coming out of time .

 

[Mike Curtis]

Thanks for your reply Dave, I was also thinking that it may be the lower key on the stator. But the lower mark seems to always be accurate to actual TDC location. This was leading me to think that it was in the top end. Maybe it is just a stretched timing chain. Or guides, or tensioner... do I have to split the case to change timing chain / guides?

[davefrombc]

Can't help  you there . I've  never had to  service the timing  chain  on  mine. If  it  is the timing  chain  itself that  is the problem  it  has to be  jumping on the  sprockets ..  Simple stretch  won't change the timing that far . Are the sprocket teeth  badly worn ?

[Mike Curtis]

No, they seem in condition. But I'm starting to look heavily at the tensioner...

[Mike Curtis]

Well, I bought a timing chain and tensioner and it solved the problem. I installed it Saturday and have put some hours on the A/C and it starts and runs great!! It starts and runs first time every time. It feels strong whith no smoke and I think its gonna make a fine bike. Also I used a solid aftermarket tensioner that seems to work very well if anyone was curious. I actually believe that the stock tensioner was the failure point. I have never been a fan of automatic tensioners. Thanks for your help davefrombc.

[mikeexplorer]

Nice, glad to see you got it running